freebsd-dev/share/man/man8/rc.subr.8

.\" 	$NetBSD: rc.subr.8,v 1.12 2004/01/06 00:52:24 lukem Exp $
.\"
.\" Copyright (c) 2002-2004 The NetBSD Foundation, Inc.
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.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Luke Mewburn.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer.
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" $FreeBSD$
.\"
.Dd January 5, 2019
.Dt RC.SUBR 8
.Os
.Sh NAME
.Nm rc.subr
.Nd functions used by system shell scripts
.Sh SYNOPSIS
.Bl -item -compact
.It
.Ic .\& Pa /etc/rc.subr
.Pp
.It
.Ic backup_file Ar action Ar file Ar current Ar backup
.It
.Ic checkyesno Ar var
.It
.Ic check_pidfile Ar pidfile Ar procname Op Ar interpreter
.It
.Ic check_process Ar procname Op Ar interpreter
.It
.Ic debug Ar message
.It
.Ic err Ar exitval Ar message
.It
.Ic force_depend Ar name
.It
.Ic info Ar message
.It
.Ic load_kld Oo Fl e Ar regex Oc Oo Fl m Ar module Oc Ar file
.It
.Ic load_rc_config Ar name
.It
.Ic load_rc_config_var Ar name Ar var
.It
.Ic mount_critical_filesystems Ar type
.It
.Ic rc_usage Ar command ...
.It
.Ic reverse_list Ar item ...
.It
.Ic run_rc_command Ar argument
.It
.Ic run_rc_script Ar file Ar argument
.It
.Ic wait_for_pids Op Ar pid ...
.It
.Ic warn Ar message
.El
.Sh DESCRIPTION
The
.Nm
script
contains commonly used shell script functions and variable
definitions which are used by various scripts such as
.Xr rc 8 .
Scripts required by ports in
.Pa /usr/local/etc/rc.d
will also eventually
be rewritten to make use of it.
.Pp
The
.Nm
functions were mostly imported from
.Nx .
.Pp
They are accessed by sourcing
.Pa /etc/rc.subr
into the current shell.
.Pp
The following shell functions are available:
.Bl -tag -width 4n
.It Ic backup_file Ar action file current backup
Make a backup copy of
.Ar file
into
.Ar current .
Save the previous version of
.Ar current
as
.Ar backup .
.Pp
The
.Ar action
argument
may be one of the following:
.Bl -tag -width ".Cm remove"
.It Cm add
.Ar file
is now being backed up by or possibly re-entered into this backup mechanism.
.Ar current
is created.
.It Cm update
.Ar file
has changed and needs to be backed up.
If
.Ar current
exists, it is copied to
.Ar backup
and then
.Ar file
is copied to
.Ar current .
.It Cm remove
.Ar file
is no longer being tracked by this backup mechanism.
.Ar current
is moved to
.Ar backup .
.El
.It Ic checkyesno Ar var
Return 0 if
.Ar var
is defined to
.Dq Li YES ,
.Dq Li TRUE ,
.Dq Li ON ,
or
.Ql 1 .
Return 1 if
.Ar var
is defined to
.Dq Li NO ,
.Dq Li FALSE ,
.Dq Li OFF ,
or
.Ql 0 .
Otherwise, warn that
.Ar var
is not set correctly.
The values are case insensitive.
.Sy Note :
.Ar var
should be a variable name, not its value;
.Ic checkyesno
will expand the variable by itself.
.It Ic check_pidfile Ar pidfile procname Op Ar interpreter
Parses the first word of the first line of
.Ar pidfile
for a PID, and ensures that the process with that PID
is running and its first argument matches
.Ar procname .
Prints the matching PID if successful, otherwise nothing.
If
.Ar interpreter
is provided, parse the first line of
.Ar procname ,
ensure that the line is of the form:
.Pp
.Dl "#! interpreter [...]"
.Pp
and use
.Ar interpreter
with its optional arguments and
.Ar procname
appended as the process string to search for.
.It Ic check_process Ar procname Op Ar interpreter
Prints the PIDs of any processes that are running with a first
argument that matches
.Ar procname .
.Ar interpreter
is handled as per
.Ic check_pidfile .
.It Ic debug Ar message
Display a debugging message to
.Va stderr ,
log it to the system log using
.Xr logger 1 ,
and
return to the caller.
The error message consists of the script name
(from
.Va $0 ) ,
followed by
.Dq Li ": DEBUG: " ,
and then
.Ar message .
This function is intended to be used by developers
as an aid to debugging scripts.
It can be turned on or off
by the
.Xr rc.conf 5
variable
.Va rc_debug .
.It Ic err Ar exitval message
Display an error message to
.Va stderr ,
log it to the system log
using
.Xr logger 1 ,
and
.Ic exit
with an exit value of
.Ar exitval .
The error message consists of the script name
(from
.Va $0 ) ,
followed by
.Dq Li ": ERROR: " ,
and then
.Ar message .
.It Ic force_depend Ar name
Output an advisory message and force the
.Ar name
service to start.
The
.Ar name
argument is the
.Xr basename 1
component of the path to the script, usually
.Pa /etc/rc.d/name .
If the script fails for any reason it will output a warning
and return with a return value of 1.
If it was successful
it will return 0.
.It Ic info Ar message
Display an informational message to
.Va stdout ,
and log it to the system log using
.Xr logger 1 .
The message consists of the script name
(from
.Va $0 ) ,
followed by
.Dq Li ": INFO: " ,
and then
.Ar message .
The display of this informational output can be
turned on or off by the
.Xr rc.conf 5
variable
.Va rc_info .
.It Ic load_kld Oo Fl e Ar regex Oc Oo Fl m Ar module Oc Ar file
Load
.Ar file
as a kernel module unless it is already loaded.
For the purpose of checking the module status,
either the exact module name can be specified using
.Fl m ,
or an
.Xr egrep 1
regular expression matching the module name can be supplied via
.Fl e .
By default, the module is assumed to have the same name as
.Ar file ,
which is not always the case.
.It Ic load_rc_config Ar name
Source in the configuration files for
.Ar name .
First,
.Pa /etc/rc.conf
is sourced if it has not yet been read in.
Then,
.Pa /etc/rc.conf.d/ Ns Ar name
is sourced if it is an existing file.
The latter may also contain other variable assignments to override
.Ic run_rc_command
arguments defined by the calling script, to provide an easy
mechanism for an administrator to override the behaviour of a given
.Xr rc.d 8
script without requiring the editing of that script.
.It Ic load_rc_config_var Ar name Ar var
Read the
.Xr rc.conf 5
variable
.Ar var
for
.Ar name
and set in the current shell, using
.Ic load_rc_config
in a sub-shell to prevent unwanted side effects from other variable
assignments.
.It Ic mount_critical_filesystems Ar type
Go through a list of critical file systems,
as found in the
.Xr rc.conf 5
variable
.Va critical_filesystems_ Ns Ar type ,
mounting each one that
is not currently mounted.
.It Ic rc_usage Ar command ...
Print a usage message for
.Va $0 ,
with
.Ar commands
being the list of valid arguments
prefixed by
.Sm off
.Dq Bq Li fast | force | one | quiet .
.Sm on
.It Ic reverse_list Ar item ...
Print the list of
.Ar items
in reverse order.
.It Ic run_rc_command Ar argument
Run the
.Ar argument
method for the current
.Xr rc.d 8
script, based on the settings of various shell variables.
.Ic run_rc_command
is extremely flexible, and allows fully functional
.Xr rc.d 8
scripts to be implemented in a small amount of shell code.
.Pp
.Ar argument
is searched for in the list of supported commands, which may be one
of:
.Bl -tag -width ".Cm restart" -offset indent
.It Cm start
Start the service.
This should check that the service is to be started as specified by
.Xr rc.conf 5 .
Also checks if the service is already running and refuses to start if
it is.
This latter check is not performed by standard
.Fx
scripts if the system is starting directly to multi-user mode, to
speed up the boot process.
.It Cm stop
If the service is to be started as specified by
.Xr rc.conf 5 ,
stop the service.
This should check that the service is running and complain if it is not.
.It Cm restart
Perform a
.Cm stop
then a
.Cm start .
Defaults to displaying the process ID of the program (if running).
.It Cm enabled
Return 0 if the service is enabled and 1 if it is not.
This command does not print anything.
.It Cm rcvar
Display which
.Xr rc.conf 5
variables are used to control the startup of the service (if any).
.El
.Pp
If
.Va pidfile
or
.Va procname
is set, also support:
.Bl -tag -width ".Cm restart" -offset indent
.It Cm poll
Wait for the command to exit.
.It Cm status
Show the status of the process.
.El
.Pp
Other supported commands are listed in the optional variable
.Va extra_commands .
.Pp
.Ar argument
may have one of the following prefixes which alters its operation:
.Bl -tag -width ".Li force" -offset indent
.It Li fast
Skip the check for an existing running process,
and sets
.Va rc_fast Ns = Ns Li YES .
.It Li force
Skip the checks for
.Va rcvar
being set to
.Dq Li YES ,
and sets
.Va rc_force Ns = Ns Li YES .
This ignores
.Ar argument Ns Va _precmd
returning non-zero, and ignores any of the
.Va required_*
tests failing, and always returns a zero exit status.
.It Li one
Skip the checks for
.Va rcvar
being set to
.Dq Li YES ,
but performs all the other prerequisite tests.
.It Li quiet
Inhibits some verbose diagnostics.
Currently, this includes messages
.Qq Starting ${name}
(as checked by
.Ic check_startmsgs
inside
.Nm )
and errors about usage of services that are not enabled in
.Xr rc.conf 5 .
This prefix also sets
.Va rc_quiet Ns = Ns Li YES .
.Em Please, note\&:
.Va rc_quiet
is not intended to completely mask all debug and warning messages,
but only certain small classes of them.
.El
.Pp
.Ic run_rc_command
uses the following shell variables to control its behaviour.
Unless otherwise stated, these are optional.
.Bl -tag -width ".Va procname" -offset indent
.It Va name
The name of this script.
This is not optional.
.It Va rcvar
The value of
.Va rcvar
is checked with
.Ic checkyesno
to determine if this method should be run.
.It Va command
Full path to the command.
Not required if
.Ar argument Ns Va _cmd
is defined for each supported keyword.
Can be overridden by
.Va ${name}_program .
.It Va command_args
Optional arguments and/or shell directives for
.Va command .
.It Va command_interpreter
.Va command
is started with:
.Pp
.Dl "#! command_interpreter [...]"
.Pp
which results in its
.Xr ps 1
command being:
.Pp
.Dl "command_interpreter [...] command"
.Pp
so use that string to find the PID(s) of the running command
rather than
.Va command .
.It Va extra_commands
Extra commands/keywords/arguments supported.
.It Va pidfile
Path to PID file.
Used to determine the PID(s) of the running command.
If
.Va pidfile
is set, use:
.Pp
.Dl "check_pidfile $pidfile $procname"
.Pp
to find the PID.
Otherwise, if
.Va command
is set, use:
.Pp
.Dl "check_process $procname"
.Pp
to find the PID.
.It Va procname
Process name to check for.
Defaults to the value of
.Va command .
.It Va required_dirs
Check for the existence of the listed directories
before running the
.Cm start
method.
The list is checked before running
.Va start_precmd .
.It Va required_files
Check for the readability of the listed files
before running the
.Cm start
method.
The list is checked before running
.Va start_precmd .
.It Va required_modules
Ensure that the listed kernel modules are loaded
before running the
.Cm start
method.
The list is checked after running
.Va start_precmd .
This is done after invoking the commands from
.Va start_precmd
so that the missing modules are not loaded in vain
if the preliminary commands indicate a error condition.
A word in the list can have an optional
.Dq Li \&: Ns Ar modname
or
.Dq Li ~ Ns Ar pattern
suffix.
The
.Ar modname
or
.Ar pattern
parameter is passed to
.Ic load_kld
through a
.Fl m
or
.Fl e
option, respectively.
See the description of
.Ic load_kld
in this document for details.
.It Va required_vars
Perform
.Ic checkyesno
on each of the list variables
before running the
.Cm start
method.
The list is checked after running
.Va start_precmd .
.It Va ${name}_chdir
Directory to
.Ic cd
to before running
.Va command ,
if
.Va ${name}_chroot
is not provided.
.It Va ${name}_chroot
Directory to
.Xr chroot 8
to before running
.Va command .
Only supported after
.Pa /usr
is mounted.
.It Va ${name}_env
A list of environment variables to run
.Va command
with.
This will be passed as arguments to the
.Xr env 1
utility.
.It Va ${name}_env_file
A file to source for environmental variables to run
.Va command
with.
Note that all the variables which are being assigned in this file are going
to be exported into the environment of
.Va command .
.It Va ${name}_fib
FIB
.Pa Routing Table
number to run
.Va command
with.
See
.Xr setfib 1
for more details.
.It Va ${name}_flags
Arguments to call
.Va command
with.
This is usually set in
.Xr rc.conf 5 ,
and not in the
.Xr rc.d 8
script.
The environment variable
.Sq Ev flags
can be used to override this.
.It Va ${name}_nice
.Xr nice 1
level to run
.Va command
as.
Only supported after
.Pa /usr
is mounted.
.It Va ${name}_limits
Resource limits to apply to
.Va command .
This will be passed as arguments to the
.Xr limits 1
utility.
By default, the resource limits are based on the login class defined in
.Va ${name}_login_class .
.It Va ${name}_login_class
Login class to use with
.Va ${name}_limits .
Defaults to
.Dq Li daemon .
.It Va ${name}_oomprotect
.Xr protect 1
.Va command
from being killed when swap space is exhausted.
If
.Dq Li YES
is used, no child processes are protected.
If
.Dq Li ALL ,
protect all child processes.
.It Va ${name}_program
Full path to the command.
Overrides
.Va command
if both are set, but has no effect if
.Va command
is unset.
As a rule,
.Va command
should be set in the script while
.Va ${name}_program
should be set in
.Xr rc.conf 5 .
.It Va ${name}_user
User to run
.Va command
as, using
.Xr chroot 8
if
.Va ${name}_chroot
is set, otherwise
uses
.Xr su 1 .
Only supported after
.Pa /usr
is mounted.
.It Va ${name}_group
Group to run the chrooted
.Va command
as.
.It Va ${name}_groups
Comma separated list of supplementary groups to run the chrooted
.Va command
with.
.It Va ${name}_prepend
Commands to be prepended to
.Va command .
This is a generic version of
.Va ${name}_env ,
.Va ${name}_fib ,
or
.Va ${name}_nice .
.It Ar argument Ns Va _cmd
Shell commands which override the default method for
.Ar argument .
.It Ar argument Ns Va _precmd
Shell commands to run just before running
.Ar argument Ns Va _cmd
or the default method for
.Ar argument .
If this returns a non-zero exit code, the main method is not performed.
If the default method is being executed, this check is performed after
the
.Va required_*
checks and process (non-)existence checks.
.It Ar argument Ns Va _postcmd
Shell commands to run if running
.Ar argument Ns Va _cmd
or the default method for
.Ar argument
returned a zero exit code.
.It Va sig_stop
Signal to send the processes to stop in the default
.Cm stop
method.
Defaults to
.Dv SIGTERM .
.It Va sig_reload
Signal to send the processes to reload in the default
.Cm reload
method.
Defaults to
.Dv SIGHUP .
.El
.Pp
For a given method
.Ar argument ,
if
.Ar argument Ns Va _cmd
is not defined, then a default method is provided by
.Ic run_rc_command :
.Bl -tag -width ".Sy Argument" -offset indent
.It Sy Argument
.Sy Default method
.It Cm start
If
.Va command
is not running and
.Ic checkyesno Va rcvar
succeeds, start
.Va command .
.It Cm stop
Determine the PIDs of
.Va command
with
.Ic check_pidfile
or
.Ic check_process
(as appropriate),
.Ic kill Va sig_stop
those PIDs, and run
.Ic wait_for_pids
on those PIDs.
.It Cm reload
Similar to
.Cm stop ,
except that it uses
.Va sig_reload
instead, and does not run
.Ic wait_for_pids .
Another difference from
.Cm stop
is that
.Cm reload
is not provided by default.
It can be enabled via
.Va extra_commands
if appropriate:
.Pp
.Dl "extra_commands=reload"
.It Cm restart
Runs the
.Cm stop
method, then the
.Cm start
method.
.It Cm status
Show the PID of
.Va command ,
or some other script specific status operation.
.It Cm poll
Wait for
.Va command
to exit.
.It Cm rcvar
Display which
.Xr rc.conf 5
variable is used (if any).
This method always works, even if the appropriate
.Xr rc.conf 5
variable is set to
.Dq Li NO .
.El
.Pp
The following variables are available to the methods
(such as
.Ar argument Ns Va _cmd )
as well as after
.Ic run_rc_command
has completed:
.Bl -tag -width ".Va rc_service" -offset indent
.It Va rc_arg
Argument provided to
.Ic run_rc_command ,
after fast and force processing has been performed.
.It Va rc_flags
Flags to start the default command with.
Defaults to
.Va ${name}_flags ,
unless overridden by the environment variable
.Sq Ev flags .
This variable may be changed by the
.Ar argument Ns Va _precmd
method.
.It Va rc_service
Path to the service script being executed, in case it needs to re-invoke itself.
.It Va rc_pid
PID of
.Va command
(if appropriate).
.It Va rc_fast
Not empty if
.Dq Li fast
prefix was used.
.It Va rc_force
Not empty if
.Dq Li force
prefix was used.
.El
.It Ic run_rc_script Ar file argument
Start the script
.Ar file
with an argument of
.Ar argument ,
and handle the return value from the script.
.Pp
Various shell variables are unset before
.Ar file
is started:
.Bd -ragged -offset indent
.Va name ,
.Va command ,
.Va command_args ,
.Va command_interpreter ,
.Va extra_commands ,
.Va pidfile ,
.Va rcvar ,
.Va required_dirs ,
.Va required_files ,
.Va required_vars ,
.Ar argument Ns Va _cmd ,
.Ar argument Ns Va _precmd .
.Ar argument Ns Va _postcmd .
.Ed
.Pp
The startup behaviour of
.Ar file
depends upon the following checks:
.Bl -enum
.It
If
.Ar file
ends in
.Pa .sh ,
it is sourced into the current shell.
.It
If
.Ar file
appears to be a backup or scratch file
(e.g., with a suffix of
.Pa ~ , # , .OLD ,
or
.Pa .orig ) ,
ignore it.
.It
If
.Ar file
is not executable, ignore it.
.It
If the
.Xr rc.conf 5
variable
.Va rc_fast_and_loose
is empty,
source
.Ar file
in a sub shell,
otherwise source
.Ar file
into the current shell.
.El
.It Ic stop_boot Op Ar always
Prevent booting to multiuser mode.
If the
.Va autoboot
variable is set to
.Ql yes ,
or
.Ic checkyesno Ar always
indicates a truth value, then a
.Dv SIGTERM
signal is sent to the parent
process, which is assumed to be
.Xr rc 8 .
Otherwise, the shell exits with a non-zero status.
.It Ic wait_for_pids Op Ar pid ...
Wait until all of the provided
.Ar pids
do not exist any more, printing the list of outstanding
.Ar pids
every two seconds.
.It Ic warn Ar message
Display a warning message to
.Va stderr
and log it to the system log
using
.Xr logger 1 .
The warning message consists of the script name
(from
.Va $0 ) ,
followed by
.Dq Li ": WARNING: " ,
and then
.Ar message .
.El
.Sh FILES
.Bl -tag -width ".Pa /etc/rc.subr" -compact
.It Pa /etc/rc.subr
The
.Nm
file resides in
.Pa /etc .
.El
.Sh SEE ALSO
.Xr rc.conf 5 ,
.Xr rc 8
.Sh HISTORY
The
.Nm
script
appeared in
.Nx 1.3 .
The
.Xr rc.d 8
support functions appeared in
.Nx 1.5 .
The
.Nm
script
first appeared in
.Fx 5.0 .